1. Technical Field
The present invention relates to an optical device and an analyzing apparatus.
2. Related Art
In recent years, the demand for a sensor used for medical diagnosis, food inspection or the like has increased, and the development of a highly sensitive small sensor has been requested. In order to meet such request, various types of sensors including one using an electrochemical technique have been studied. Among these, interest in a sensor using surface plasmon resonance has increased because the sensor can be integrated, manufactured at low cost, and used in any measurement environment.
For example, JP-A-2007-240361 discloses a surface plasmon resonance sensor in which light is coupled to a surface plasmon polariton by a metal periodic structure.
However, in this sensor, since the resonant condition of the surface plasmon has a large selectivity to an incident angle of light, only light of a specific incident angle is coupled to the surface plasmon polariton. Thus, only apart of the light concentrated by an objective lens is coupled to the surface plasmon polariton, and there is a problem in that a sufficient sensing sensitivity cannot be obtained.